\section[TcBinds]{TcBinds}
\begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
module TcBinds ( tcLocalBinds, tcTopBinds,
tcHsBootSigs, tcMonoBinds,
TcPragFun, tcSpecPrag, tcPrags, mkPragFun,
import TcMType
import TcType
import {- Kind parts of -} Type
+import Coercion
import VarEnv
import TysPrim
import Id
import IdInfo
-import Var ( TyVar )
+import Var ( TyVar, varType )
import Name
import NameSet
import NameEnv
bindLocalInsts :: TopLevelFlag -> TcM ([LHsBinds TcId], [TcId], a) -> TcM ([LHsBinds TcId], a)
bindLocalInsts top_lvl thing_inside
| isTopLevel top_lvl = do { (binds, ids, thing) <- thing_inside; return (binds, thing) }
- -- For the top level don't bother will all this bindInstsOfLocalFuns stuff.
+ -- For the top level don't bother with all this bindInstsOfLocalFuns stuff.
-- All the top level things are rec'd together anyway, so it's fine to
-- leave them to the tcSimplifyTop, and quite a bit faster too
generalise dflags top_lvl bind_list sig_fn mono_bind_infos lie_req
-- BUILD THE POLYMORPHIC RESULT IDs
- ; let dict_ids = map instToId dicts
- ; exports <- mapM (mkExport top_lvl prag_fn tyvars_to_gen (map idType dict_ids))
+ ; let dict_vars = map instToVar dicts -- May include equality constraints
+ ; exports <- mapM (mkExport top_lvl prag_fn tyvars_to_gen (map varType dict_vars))
mono_bind_infos
; let poly_ids = [poly_id | (_, poly_id, _, _) <- exports]
; traceTc (text "binding:" <+> ppr (poly_ids `zip` map idType poly_ids))
; let abs_bind = L loc $ AbsBinds tyvars_to_gen
- dict_ids exports
+ dict_vars exports
(dict_binds `unionBags` binds')
; return ([unitBag abs_bind], poly_ids) -- poly_ids are guaranteed zonked by mkExport
= do { warn_missing_sigs <- doptM Opt_WarnMissingSigs
; let warn = isTopLevel top_lvl && warn_missing_sigs
; (tvs, poly_id) <- mk_poly_id warn mb_sig
+ -- poly_id has a zonked type
- ; poly_id' <- zonkId poly_id
- ; prags <- tcPrags poly_id' (prag_fn poly_name)
+ ; prags <- tcPrags poly_id (prag_fn poly_name)
-- tcPrags requires a zonked poly_id
- ; return (tvs, poly_id', mono_id, prags) }
+ ; return (tvs, poly_id, mono_id, prags) }
where
poly_ty = mkForAllTys inferred_tvs (mkFunTys dict_tys (idType mono_id))
- mk_poly_id warn Nothing = do { missingSigWarn warn poly_name poly_ty
- ; return (inferred_tvs, mkLocalId poly_name poly_ty) }
+ mk_poly_id warn Nothing = do { poly_ty' <- zonkTcType poly_ty
+ ; missingSigWarn warn poly_name poly_ty'
+ ; return (inferred_tvs, mkLocalId poly_name poly_ty') }
mk_poly_id warn (Just sig) = do { tvs <- mapM zonk_tv (sig_tvs sig)
; return (tvs, sig_id sig) }
tcSpecPrag :: TcId -> LHsType Name -> InlineSpec -> TcM Prag
tcSpecPrag poly_id hs_ty inl
- = do { spec_ty <- tcHsSigType (FunSigCtxt (idName poly_id)) hs_ty
- ; (co_fn, lie) <- getLIE (tcSubExp (idType poly_id) spec_ty)
+ = do { let name = idName poly_id
+ ; spec_ty <- tcHsSigType (FunSigCtxt name) hs_ty
+ ; (co_fn, lie) <- getLIE (tcSubExp (SpecPragOrigin name) (idType poly_id) spec_ty)
; extendLIEs lie
; let const_dicts = map instToId lie
; return (SpecPrag (mkHsWrap co_fn (HsVar poly_id)) spec_ty const_dicts inl) }
where
bndrs = bndrNames mono_infos
sigs = [sig | (_, Just sig, _) <- mono_infos]
- tau_tvs = foldr (unionVarSet . exactTyVarsOfType . getMonoType) emptyVarSet mono_infos
- -- NB: exactTyVarsOfType; see Note [Silly type synonym]
- -- near defn of TcType.exactTyVarsOfType
+ get_tvs | isTopLevel top_lvl = tyVarsOfType -- See Note [Silly type synonym] in TcType
+ | otherwise = exactTyVarsOfType
+ tau_tvs = foldr (unionVarSet . get_tvs . getMonoType) emptyVarSet mono_infos
is_mono_sig sig = null (sig_theta sig)
doc = ptext SLIT("type signature(s) for") <+> pprBinders bndrs
unify_ctxt sig@(TcSigInfo { sig_theta = theta })
= setSrcSpan (instLocSpan (sig_loc sig)) $
addErrCtxt (sigContextsCtxt sig1 sig) $
- unifyTheta theta1 theta
+ do { cois <- unifyTheta theta1 theta
+ ; -- Check whether all coercions are identity coercions
+ -- That can happen if we have, say
+ -- f :: C [a] => ...
+ -- g :: C (F a) => ...
+ -- where F is a type function and (F a ~ [a])
+ -- Then unification might succeed with a coercion. But it's much
+ -- much simpler to require that such signatures have identical contexts
+ checkTc (all isIdentityCoercion cois)
+ (ptext SLIT("Mutually dependent functions have syntactically distinct contexts"))
+ }
checkSigsTyVars :: [TcTyVar] -> [TcSigInfo] -> TcM [TcTyVar]
checkSigsTyVars qtvs sigs